Text messaging (e.g., Short Message Service (SMS)) is a popular feature of telecommunications systems to facilitate the exchange of small amounts of data between fixed and/or mobile devices. Network operators can provide text messaging as a circuit-switched (CS) service in second generation (2G) (e.g., Global System for Mobile communications (GSM), Code Division Multiple Access (CDMA), General Packet Radio Service (GPRS), Enhanced Data rates for GSM Evolution (EDGE)) and third generation (3G) (e.g., Universal Mobile Telecommunications Systems (UMTS), Wideband CDMA (WCDMA), CDMA2000, High-Speed Packet Access (HSPA)) mobile networks. Long Term Evolution (LTE) (sometimes also referred to as Evolved Packet System (EPS)) is a wireless broadband technology developed by the Third Generation Partnership Project (3GPP) to succeed 2G/3G. LTE and later generation telecommunication networks may operate exclusively in the packet-switched (PS) domain while 2G/3G networks can operate in both the CS and PS domains. To enable network operators to continue to support certain CS services in a PS network, the 3GPP developed CS Fallback (CSFB) for voice and SMS over SGs for text messaging (e.g., as specified in 3GPP TS 29.118, which is fully incorporated herein by reference).
SMS over SGs allows the transmission of native SMS from CS infrastructure (e.g., 2G/3G core networks) to a Mobile Station (MS) or User Equipment (MS/UE) connected to a PS radio access network (e.g., 4G, 5G, and later generation networks). The SGs interface can be used to handle mobility management and paging procedures between the CS and PS domains, and to deliver Mobile Originating SMS (MO-SMS) and Mobile Terminating SMS (MT-SMS). Current implementations of SMS over SGs limit recovery from an SMS delivery failure (e.g., due to virtual location register (VLR) failure) to events triggered by the MS/UE (e.g., MO-SMS). However, it can sometimes be preferable to initiate recovery from an SMS delivery failure from the network (e.g., MT-SMS).